The rise of predation in Jurassic lampreys

Lampreys, one of two living lineages of jawless vertebrates, are always intriguing for their feeding behavior via the toothed suctorial disc and life cycle comprising the ammocoete, metamorphic, and adult stages. However, they left a meager fossil record, and their evolutionary history remains elusive. Here we report two superbly preserved large lampreys from the Middle-Late Jurassic Yanliao Biota of North China and update the interpretations of the evolution of the feeding apparatus, the life cycle, and the historic biogeography of the group. These fossil lampreys’ extensively toothed feeding apparatus differs radically from that of their Paleozoic kin but surprisingly resembles the Southern Hemisphere pouched lamprey, which foreshadows an ancestral flesh-eating habit for modern lampreys. Based on the revised petromyzontiform timetree, we argued that modern lampreys’ three-staged life cycle might not be established until the Jurassic when they evolved enhanced feeding structures, increased body size and encountered more penetrable host groups. Our study also places modern lampreys’ origin in the Southern Hemisphere of the Late Cretaceous, followed by an early Cenozoic anti-tropical disjunction in distribution, hence challenging the conventional wisdom of their biogeographical pattern arising from a post-Cretaceous origin in the Northern Hemisphere or the Pangean fragmentation in the Early Mesozoic.

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Data collection The data used in this study followed that in previous relevant study plus a dozen of newly defined morphological characters tudy and the Statistical analyses were performed using the Bayesian phylogenetic inference software MrBayes (https://github.com/NBISweden/MrBayes).We describe the models, priors andMarkov chain Monte Carlo (MCMC) settings for the analysis in the Methods section in the main text.

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This study described two new fossil lampreys from the Jurassic of North China.It presented new interpretations of the evolution of the feeding apparatus, body size, life cycle pattern, and the historic biogeography of lampreys.
Four fossil lampreys(jawless vertebrates), two of Yanliaomyzon occisor, and two of Yanliaomyzon ingensdentes.We chose them because they preserved structures of the feeding apparatus and the intestine content which can uncover the feeding biology of these fossil lampreys and shed new light on the evolution of lampreys.The colleagues of IVPP conducted fieldwork in the fossil localities and then collected the fossil materials and finnaly delivered them to the first author of this study.The sample sizes include the details of the feeding appratus and the postcranial part of the lampreys and therefore is sufficient.
The morphological data was collected via careful observation on the specimens under the microscobe Zeiss Stemi 305 and Nikon 745T and codified as discrete characters in the matrix by Feixiang Wu, and then delivered the date to Chi Zhang for analyses

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Blinding was not relevant for data collection as samples were selected based on their location within the stratigraphy.Blinding was also not relevant for downstream analysis as previously established analysis pipelines was used for the processing of the Jianchang County, Lingyuan City, Liaoning Province, and Wubaiding section, Reshuitang Town, Lingyuan City, Liaoning Province, China.

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No randomization procedure was applicable because it was not necessary for the type of study we conducted, it is a study about the fossils which are which are always incomplete and unreplaceable.Temperate region with plains and small hills in North China.The annual temperature is 3℃ ~16℃.Fossil localities are near towns and cities.
Nanshimen (40°31'52"N, 119°29'11"E), Gangou Town, Qinglong County, Hebei Province; Toudaoyingzi (40°46'N 119°26'E), Jianchang County, Liaoning Province; Wubaiding section(41°22'9"N, 119°23'38"E), Reshuitang Town, Lingyuan City, Liaoning Province, China.Prof. Xiaoling Wang kept some of the specimens and delivered the holotype of Yanliaomyzon occisor to Professor Mee-mann Chang (IVPP) then.In 2019 and 2020 they handed over these lamprey materials to the first author of this work.In the May of 2020, the first author, together with Dr. Haibing Wang and Dr. Zhiqiang Yu, Wei Zhou (IVPP) went (driving a car by Zhou from Beijing to the fossil localities) to check the lithological, stratigraphical and sedimentary setting of relevant sections.The palaeontologists of IVPP are free to go there for fieldwork and collect specimens, no special permission is necessary for the scientific exploration in this region.No importion or exportion is involved in this study.
No disturbances were caused during the study.

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The specimens of Yanliaomyzon occisor are from Nanshimen Village, Gangou Town, Qinglong County, Hebei Province and Toudaoyingzi Town, Jianchang County, Liaoning Province.Those of Yanliaomyzon ingensdentes are from Wubaiding section, Reshuitang Town, Lingyuan City, Liaoning Province, China .In these localities, the researchers are free to conduct the field work.People who want to check the specimen can get the access via contacting the corresponding authors.methods , J ' information on the approval of the study protocol must also be provided in the N/A manuscript 丿 Field-specific reporting Please select the one below that is the best fit for your research.If you are not sure, read the appropriate sections before making your selection.口Life sciences □ Behavioural & social sciences 口 Ecological, evolutionary & environmental sciences For a reference copy of the document with all sections, see� For qualitative data, please indicate whether data saturation was considered, and what criteria were used to decide that no further sampling was needed Nthe data collection procedure, including the instruments or devices used to record the data (e.g.pen and paper, computer, eye tracker, video or audio equipment丿whether anyone was present besides the participant(s) and the researcher, and whether the researcher was blind to experimental condition and/or the study hypothesis during data collection.
Xiaolin Wang and in 2014 by Min Wang .Data collection from the fossils started in May, 2020 and ossils are from the fossil localities of Nanshimen Village , Gangou Town, Qinglong County, Hebei Province, and Toudaoyingzi, data

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work, collection and Did the study involve field work?口 Yes 仁] No transport 、 In 2008

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2009, 2014, Prof. Xiaoling Wang and Min Wang of the Insititute of Vertebrate Paleontology and Paleoanthropology (IVPP), CAS conducted fieldwork in the fossil localities and collected fossil materials reported herein.
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